With the development of a technique for miniaturizing a semiconductor device, the degree of integration of a microcontroller has been increased year by year. Accordingly, the leakage current of a variety of semiconductor elements (e.g., a transistor and the like) provided inside the microcontroller has been increased, which has resulted in a large increase in power consumption of the microcontroller. Thus, one of important issues in recent years is to reduce power consumption of a microcontroller.
As one of methods for reducing power consumption of a microcontroller, there is a technique in which a circuit block unnecessary for operation of the microcontroller, of circuit blocks in the microcontroller, is shifted to a low power consumption mode (see Patent Document 1).